Hangovers don't just happen like a headache, an ingrown toenail, or cancer. Looking for a cure for a hangover is largely too late. Prevention is the key but there are a few things that can be done to help get through the day after drinking too heavily.
Step 1: Prevention
One of the best things to do before drinking is to eat a hearty meal. If you can't do that gobble down the peanuts, popcorn, or whatever other food is available where you are drinking. Drinking on an empty stomach is unwise.
Downing a quart of water before the first drink will give your body the fluid it needs and help divert the absorption of the alcohol into your system.
Step 2: During
Try to drink only one alcoholic beverage per hour. Sticking with the same drink for the whole night tends to lead to less complications later.
Red wine and other dark liquors usually result in a higher chance for a hangover. The less expensive the alcohol the more toxin and thus the greater chance for a hangover.
Drinking water or juice in between alcohol will keep you hydrated (alcohol is a diuretic and removes more fluid from you than it contributes). The liver needs water to remove toxins from the body (yes, alcohol is a toxin) and the sooner the liver can get to work the better.